The implantation of fertilized ova and the formation of the placenta are crucial steps in reproduction. This review summarizes current information about these steps, including some of the molecular mechanisms that mediate them and how they may go awry, with consequent loss of the pregnancy.

Implantation and the survival of early pregnancy.

Defects in the function of cellular organelles such as peroxisomes, lysosomes and mitochondria are well-known causes of human diseases. Recently, another organelle has also been added to this list. Cilia--tiny hair-like organelles attached to the cell surface--are located on almost all polarized cell types of the human body and have been adapted as versatile tools for various cellular functions, explaining why cilia-related disorders can affect many organ systems. Several molecular mechanisms involved in cilia-related disorders have been identified that affect the structure and function of distinct cilia types.

When cilia go bad: cilia defects and ciliopathies

The primary function of the corpus luteum is secretion of the hormone progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follic...

https://www.physiology.org/doi/pdf/10.1152/physrev.2000.80.1.1

Mechanisms Controlling the Function and Life Span of the Corpus Luteum

Publisher Summary This chapter discusses the insulin-like growth factor (IGF) binding proteins—namely, IGF-I and IGF-II The IGFs are purified from human plasma and cell culture medium by virtue of their ability to stimulate the growth of cartilage or cultured fibroblasts, or their insulin-like activity The IGFs are synthesized in many fetal and postnatal tissues and are capable of acting locally IGF-I and IGF-II are single-chain 75-kDa polypeptides that are chemically related to insulin They bind with high affinity to IGF-I receptors that are thought to mediate most of their biological actions The IGF-I receptor is a homolog of the insulin receptor, having a heterotetrameric structure and a tyrosine kinase domain in the cytoplasmic portion of the β-subunit that phosphorylates the receptor and other substrates, and presumably is involved in transmembrane signaling Hybrid receptors consisting of one αβ IGF-I receptor heterodimer and one αβ insulin receptor heterodimer are described IGF-II also binds with high affinity to the IGF-II/Mannose 6-phosphate receptor IGF-II added with the IGF-II/Mannose 6-phosphate receptor stimulated the activation of the guanosine triphosphate (GTP) binding protein G i-2  The IGFs participate in the physiological growth of the developing child, fetus, and embryo

Insulin-like growth factor binding proteins.

Human cartilage gp-39, a major secretory product of articular chondrocytes and synovial cells, is a mammalian member of a chitinase protein family.

Oviducts were obtained from women who elected to undergo sterilization either during a normal menstrual cycle, after the first trimester of pregnancy, or in the puerperium. The percent of ciliated cells, cell height and morphology of the fimbria and ampulla were determined and correlated with the stage of the reporductive cycle and plasma levels of the ovarian steroids. Mature ciliated and secretory cells were observed only at mid-cycle. Atrophy, deciliation and loss of secretory activity coincided with elevated levels of serum progesterone. These degenerative processes continued during pregnancy. Ciliation, hypertrophy, and restoration of secretory activity occurred when serum progesterone was essentially undetectable and estradiol relatively low. During each menstrual cycle the secretory cells were observed to undergo a complete cycle of dedifferentiation-differentiation, whereas 10--12% of the ciliated cells lost and regenerated their celia. Ciliogenic cells were frequently present in the epithelium obtained from women in the mid-follicular phase. Fibrous granules, deuterosomes, procentrioles and ciliary buds were observed in the apex of these cells. Plasma levels of estradiol were higher during periods of atrophy and deciliation than they were during periods of hypertrophy and reciliation. It appears that the serum levels of estradiol were adequate to maintain a mature epithelium at all the reproductive stages included in this study. However, progesterone, when present, blocked the growth-promoting effect of estradiol in the oviduct.

Cyclic changes in ciliation, secretion and cell height of the oviductal epithelium in women.

Published reports indicate that in several mammalian species the oviduct synthesizes and secretes specific glycoproteins which are components of the luminal fluids at the time of ovulation and fertilization. The present study characterized the secretory glycoproteins synthesized by the bovine oviduct at estrus. Oviducts obtained from four crossbred cows in estrus were flushed with saline, and segments of the ampullary and isthmic regions were fixed for immunocytochemical analyses. The remainder of the tissue was subjected to explant culture for 24 h in medium containing either 3H-leucine or 3H-glucosamine. Analysis of culture media by one- and two-dimensional SDS-PAGE followed by fluorography indicated that both the ampullary and isthmic regions synthesized a major class of Mr 97,000 glycoproteins with isoelectric points ranging from 5.5 to 8.1. A polyclonal antibody was generated to the glycoproteins after their isolation by gel filtration followed by electrophoretic separation. Western blot analysis of oviductal culture media indicated that the antisera cross-reacted with a doublet at Mr 97,000 and to a lesser extent with two additional bands at Mr greater than 200,000. Immunoreactive antigens were not identified in serum or in culture media of ovary, uterus, and nonreproductive tract tissues. The Mr 97,000 glycoproteins were present in oviductal flushings obtained from cows in estrus. They were also detected to a lesser degree in oviductal flushings obtained from cows at Days 5, 10, 15, and 18 of the estrous cycle, with the least amount of immunoreactivity being observed in Day 10 samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and characterization of bovine oviductal glycoproteins synthesized at estrus.

A 120-kDa oviduct-specific glycoprotein is synthesized and secreted into the oviductal lumen during estrogen dominance in the human. The objective of this investigation was to clone, sequence, and characterize the cDNA to this core protein. Rapid amplification of cDNA ends was used to clone a contiguous 3' cDNA end and 5' cDNA end. The total length of the cDNA was determined to be 2.2 kb by sequence analysis and exhibited a 92% sequence identity with the comparable overlapping baboon cDNA (1.2 kb). A high degree of homology was found to the N-terminal sequence of hamster oviductin and the partial sequence of a homologous baboon and bovine oviduct glycoprotein. Northern blots revealed a single mRNA species of 2.4 kb. Using RNA from various tissues of an estrogen-treated baboon, we found that the mRNA for the oviductal glycoprotein was present only in the oviduct. Hybridization was detected to an mRNA of similar size from oviductal tissue of the baboon, hamster, and mouse and to an mRNA of slightly smaller size in the rabbit, cow, and cat but not to any mRNA species from rat oviductal RNA. Slotblot analysis showed that the message was present in significantly greater (p < 0.05) concentrations in RNA from oviductal tissue from the late follicular stage than from the early follicular, early or late luteal, or postpartum stages. In conclusion, we have isolated the complete cDNA for a human oviductal glycoprotein. The presence of significantly greater amounts of the mRNA during the late follicular phase of the menstrual cycle is consistent with the proposed estrogen control. The mRNA for the oviductal glycoprotein is present only in the oviduct of an estrogen-treated baboon, and a cross-hybridizing RNA is found in oviductal RNA from various mammals.

Complementary Deoxyribonucleic Acid Cloning and Molecular Characterization of an Estrogen-Dependent Human Oviductal Glycoprotein

The purpose of this study was to identify major proteins synthesized by the human oviduct and to determine if the ability of the human oviduct to synthesize these proteins was correlated with a specific stage(s) of the menstrual cycle. Oviducts, obtained from normal menstrual and immediately postpartum women, were minced and cultured in the presence of labeled precursors. The culture medium was analyzed for newly synthesized proteins by electrophoresis, followed by fluorography. One-dimensional gel electrophoretic analysis of culture medium of oviducts obtained at midcycle revealed a major diffuse band in the 120,000–130,000 mol wt (Mr) region which was greatly diminished in intensity or nondetectable in the media of oviducts obtained at all other stages of the cycle. Twodimensional gel electrophoresis resolved the 120,000–130,000 Mr region into two major proteins, one basic and one acidic. Both proteins were intensely labeled with glucosamine, and the basic protein also incorporated leucine and methionin...

The in vitro synthesis and release of proteins by the human oviduct.

The estrogen-dominated baboon oviductal epithelium synthesizes and secretes a family of oviduct-specific glycoproteins. The objective of this study was to determine if these glycoproteins become associated with ova and early embryos. Ovarian and oviductal eggs obtained from superovulated baboons 72 h post-hCG were subjected to an indirect immunofluorescent assay that used a polyclonal antibody prepared toward the baboon oviduct-specific glycoproteins. Oviductal ova as well as 2-cell and 4-cell embryos showed intense, specific fluorescence within their zonae pellucidae. Ovarian ova did not exhibit fluorescence. Oviductal eggs were also fixed and processed for peroxidase-antiperoxidase immunocytochemistry and colloidal gold immunoelectron microscopy to confirm the immunofluorescent data and to determine the subcellular distribution of the antigens. Oviductal ova as well as 2-cell and 3-cell embryos exhibited immunolabeling localized within the zona. Gold particles were distributed uniformly throughout the width of the zona. Occasional groupings of gold particles were observed within the zona. Also, in most eggs, immunoreactivity was observed associated with flocculent material in the perivitelline space as well as the vitelline membrane. Furthermore, immunogold labeling above background level was noted in the cytoplasm of the eggs, particularly in the blastomeres of 3-cell embryos. Collectively, these results indicate that baboon estrogen-dependent oviductal secretory glycoproteins become intimately associated with oviductal ova and with embryos.

Harold G. Verhage

Papers

Cyclic changes in ciliation, secretion and cell height of the oviductal epithelium in women.

Identification and characterization of bovine oviductal glycoproteins synthesized at estrus.

Complementary Deoxyribonucleic Acid Cloning and Molecular Characterization of an Estrogen-Dependent Human Oviductal Glycoprotein

The in vitro synthesis and release of proteins by the human oviduct.

Localization of oviductal glycoproteins within the zona pellucida and perivitelline space of ovulated ova and early embryos in baboons (Papio anubis).